This invention relates to RF connectors. Proper torque must be applied to a mated pair of coaxial connectors to ensure consistent and repeatable tests of coaxial devices under test and this is especially true in the case of calibration of any test instrument such as network analyzers or other test instrumentation having coaxial test ports.
The sex of coaxial connectors is conventionally identified by the configuration of the inner conductor center contacts. If a connector has a pin then it is considered a male connector; if it has a socket then it is considered a female connector. The outer conductor of the female connector has male threads and the male connector has a connector nut with female threads, configured to engage the male threads on the female connector body. This rule will almost always apply except in the case where the connectors are hermaphrodite or a special configuration where the sex is reversed to accommodate polarization.
Singular solid plastic or metal spin rings have been used, with a female hex feature in the middle, corresponding to the hex nut size, a typical size being approximately 5/16 inch thick and having an outside diameter of ¾ inch approximate, with external features (bumps, hex, knurl, etc.) to assist in gripping or rotating to loosen or tighten the male coaxial connector to a mating female connector. Some of these spin rings have a slot to allow clearance for a 0.086 or 0.141 diameter coaxial cable when the spin ring is introduced from the rear. This device does not apply a pre-set torque to the mated pair of connectors when coupled and tightened. By its nature, the device does not provide electrical measurement repeatability from mating to mating due to the inconsistent pressure applied at the mating interface plane of the connectors.
Commercially available torque wrenches have an open end wrench of the appropriate size to mate with the hex nut on the applicable connector and a handle typically 5-6 inches long and has a pre-set torque value. This handle slips and dis-engages when the pre-set torque value is reached, ensuring that the connected pair of connectors will not exceed the torque specifications for the applicable mated pair.
Typically a spin ring is left on the connector during test and cannot be removed to allow the use of a torque wrench to achieve the torque specification. Conversely the spin ring (in most configurations of connectors) cannot be used if it is necessary to use the torque wrench to apply torque to the coupled connectors.
In the case of the hex coupling nuts that are permanently fastened to the male or hermaphrodite (sexless) coaxial connectors there are no provisions built into the nuts to apply the correct torque to the coupled pair of connectors.